In general, a printed circuit board (PCB) refers to a circuit board in which various kinds of parts are densely mounted on a flat plate made of phenol resin or epoxy resin, and curtailed circuits to connect the parts to each other are densely provided and fixed.
In this case, the PCB is manufactured in such a manner that a thin plate such as copper foil is attached to one side of a phenol resin insulating plate or an epoxy resin insulating plate, and etched (remaining portions except for circuits on a circuit line are corroded and thus removed) according to the interconnection pattern of circuits to form a desirable circuit, and the resulting structure is bored to mount parts therein.
In addition, the PCB is classified into a single-side PCB, a double-side PCB, and a multi-layer PCB according to the number of interconnection circuit surfaces. As the PCB has more many layers, the PCB represents the superior ability to mount parts so that the PCB having many layers is applied to high precision products.
The single-side PCB is mainly made of a phenol base substrate and applied to products, such as a radio set, a telephone, or a simple measurement instrument, the circuitry of which is not complicated.
In addition, the double-side PCB is mainly made of an epoxy resin base substrate, and applied to products, such as color TV sets, VTRs, or facsimiles, the circuitry of which is relatively complicated.
Furthermore, the multi-layer PCB is applied to highly precise apparatuses, such as at least 32 bit-computers, electronic switching systems, and high performance communication apparatuses.
Meanwhile, recently, as the electronic industry has been developed, a flexible PCB has been commercialized in order to flexibly cope with a case that a circuit plate must be moved similarly to automatic appliances or camcorders and a case that a circuit plate must be bent when inserting and constructing parts. In addition, various researches and studies on the flexible substrate capable of satisfying higher reliability have been performed.